//     uuid.js
//
//     Copyright (c) 2010-2012 Robert Kieffer
//     MIT License - http://opensource.org/licenses/mit-license.php

/*global window, require, define */
(function(_window) {
	'use strict';



	// Unique ID creation requires a high quality random # generator.  We feature
	// detect to determine the best RNG source, normalizing to a function that
	// returns 128-bits of randomness, since that's what's usually required
	var _rng, _mathRNG, _nodeRNG, _whatwgRNG, _previousRoot;

	function setupBrowser() {
		// Allow for MSIE11 msCrypto
		//var _crypto = _window.crypto || _window.msCrypto;
		var crypto = {}
		var _crypto = crypto || _window.crypto || _window.msCrypto;

		if (!_rng && _crypto && _crypto.getRandomValues) {
			// WHATWG crypto-based RNG - http://wiki.whatwg.org/wiki/Crypto
			//
			// Moderately fast, high quality
			try {
				var _rnds8 = new Uint8Array(16);
				_whatwgRNG = _rng = function whatwgRNG() {
					_crypto.getRandomValues(_rnds8);
					return _rnds8;
				};

				_rng();
			} catch (e) {}
		}

		if (!_rng) {
			// Math.random()-based (RNG)
			//
			// If all else fails, use Math.random().  It's fast, but is of unspecified
			// quality.
			var _rnds = new Array(16);
			_mathRNG = _rng = function() {
				for (var i = 0, r; i < 16; i++) {
					if ((i & 0x03) === 0) {
						r = Math.random() * 0x100000000;
					}
					_rnds[i] = r >>> ((i & 0x03) << 3) & 0xff;
				}

				return _rnds;
			};
			if ('undefined' !== typeof console && console.warn) {
				// console.warn("[SECURITY] node-uuid: crypto not usable, falling back to insecure Math.random()");
			}
		}
	}

	setupBrowser();

	// Buffer class to use
	var BufferClass = ('function' === typeof Buffer) ? Buffer : Array;

	// Maps for number <-> hex string conversion
	var _byteToHex = [];
	var _hexToByte = {};
	for (var i = 0; i < 256; i++) {
		_byteToHex[i] = (i + 0x100).toString(16).substr(1);
		_hexToByte[_byteToHex[i]] = i;
	}

	// **`parse()` - Parse a UUID into it's component bytes**
	function parse(s, buf, offset) {
		var i = (buf && offset) || 0,
			ii = 0;

		buf = buf || [];
		s.toLowerCase().replace(/[0-9a-f]{2}/g, function(oct) {
			if (ii < 16) { // Don't overflow!
				buf[i + ii++] = _hexToByte[oct];
			}
		});

		// Zero out remaining bytes if string was short
		while (ii < 16) {
			buf[i + ii++] = 0;
		}

		return buf;
	}

	// **`unparse()` - Convert UUID byte array (ala parse()) into a string**
	function unparse(buf, offset) {
		var i = offset || 0,
			bth = _byteToHex;
		return bth[buf[i++]] + bth[buf[i++]] +
			bth[buf[i++]] + bth[buf[i++]] + '-' +
			bth[buf[i++]] + bth[buf[i++]] + '-' +
			bth[buf[i++]] + bth[buf[i++]] + '-' +
			bth[buf[i++]] + bth[buf[i++]] + '-' +
			bth[buf[i++]] + bth[buf[i++]] +
			bth[buf[i++]] + bth[buf[i++]] +
			bth[buf[i++]] + bth[buf[i++]];
	}

	// **`v1()` - Generate time-based UUID**
	//
	// Inspired by https://github.com/LiosK/UUID.js
	// and http://docs.python.org/library/uuid.html

	// random #'s we need to init node and clockseq
	var _seedBytes = _rng();

	// Per 4.5, create and 48-bit node id, (47 random bits + multicast bit = 1)
	var _nodeId = [
		_seedBytes[0] | 0x01,
		_seedBytes[1], _seedBytes[2], _seedBytes[3], _seedBytes[4], _seedBytes[5]
	];

	// Per 4.2.2, randomize (14 bit) clockseq
	var _clockseq = (_seedBytes[6] << 8 | _seedBytes[7]) & 0x3fff;

	// Previous uuid creation time
	var _lastMSecs = 0,
		_lastNSecs = 0;

	// See https://github.com/broofa/node-uuid for API details
	function v1(options, buf, offset) {
		var i = buf && offset || 0;
		var b = buf || [];

		options = options || {};

		var clockseq = (options.clockseq != null) ? options.clockseq : _clockseq;

		// UUID timestamps are 100 nano-second units since the Gregorian epoch,
		// (1582-10-15 00:00).  JSNumbers aren't precise enough for this, so
		// time is handled internally as 'msecs' (integer milliseconds) and 'nsecs'
		// (100-nanoseconds offset from msecs) since unix epoch, 1970-01-01 00:00.
		var msecs = (options.msecs != null) ? options.msecs : new Date().getTime();

		// Per 4.2.1.2, use count of uuid's generated during the current clock
		// cycle to simulate higher resolution clock
		var nsecs = (options.nsecs != null) ? options.nsecs : _lastNSecs + 1;

		// Time since last uuid creation (in msecs)
		var dt = (msecs - _lastMSecs) + (nsecs - _lastNSecs) / 10000;

		// Per 4.2.1.2, Bump clockseq on clock regression
		if (dt < 0 && options.clockseq == null) {
			clockseq = clockseq + 1 & 0x3fff;
		}

		// Reset nsecs if clock regresses (new clockseq) or we've moved onto a new
		// time interval
		if ((dt < 0 || msecs > _lastMSecs) && options.nsecs == null) {
			nsecs = 0;
		}

		// Per 4.2.1.2 Throw error if too many uuids are requested
		if (nsecs >= 10000) {
			throw new Error('uuid.v1(): Can\'t create more than 10M uuids/sec');
		}

		_lastMSecs = msecs;
		_lastNSecs = nsecs;
		_clockseq = clockseq;

		// Per 4.1.4 - Convert from unix epoch to Gregorian epoch
		msecs += 12219292800000;

		// `time_low`
		var tl = ((msecs & 0xfffffff) * 10000 + nsecs) % 0x100000000;
		b[i++] = tl >>> 24 & 0xff;
		b[i++] = tl >>> 16 & 0xff;
		b[i++] = tl >>> 8 & 0xff;
		b[i++] = tl & 0xff;

		// `time_mid`
		var tmh = (msecs / 0x100000000 * 10000) & 0xfffffff;
		b[i++] = tmh >>> 8 & 0xff;
		b[i++] = tmh & 0xff;

		// `time_high_and_version`
		b[i++] = tmh >>> 24 & 0xf | 0x10; // include version
		b[i++] = tmh >>> 16 & 0xff;

		// `clock_seq_hi_and_reserved` (Per 4.2.2 - include variant)
		b[i++] = clockseq >>> 8 | 0x80;

		// `clock_seq_low`
		b[i++] = clockseq & 0xff;

		// `node`
		var node = options.node || _nodeId;
		for (var n = 0; n < 6; n++) {
			b[i + n] = node[n];
		}

		return buf ? buf : unparse(b);
	}

	// **`v4()` - Generate random UUID**

	// See https://github.com/broofa/node-uuid for API details
	function v4(options, buf, offset) {
		// Deprecated - 'format' argument, as supported in v1.2
		var i = buf && offset || 0;

		if (typeof(options) === 'string') {
			buf = (options === 'binary') ? new BufferClass(16) : null;
			options = null;
		}
		options = options || {};

		var rnds = options.random || (options.rng || _rng)();

		// Per 4.4, set bits for version and `clock_seq_hi_and_reserved`
		rnds[6] = (rnds[6] & 0x0f) | 0x40;
		rnds[8] = (rnds[8] & 0x3f) | 0x80;

		// Copy bytes to buffer, if provided
		if (buf) {
			for (var ii = 0; ii < 16; ii++) {
				buf[i + ii] = rnds[ii];
			}
		}

		return buf || unparse(rnds);
	}

	// Export public API
	var uuid = v4;
	uuid.v1 = v1;
	uuid.v4 = v4;
	uuid.parse = parse;
	uuid.unparse = unparse;
	uuid.BufferClass = BufferClass;
	uuid._rng = _rng;
	uuid._mathRNG = _mathRNG;
	uuid._nodeRNG = _nodeRNG;
	uuid._whatwgRNG = _whatwgRNG;


	if (('undefined' !== typeof module) && module.exports) {
		// Publish as node.js module
		module.exports = uuid;
	} else if (typeof define === 'function' && define.amd) {
		// Publish as AMD module
		define(function() {
			return uuid;
		});
	} else {
		// Publish as global (in browsers)
		_previousRoot = _window.uuid;

		// **`noConflict()` - (browser only) to reset global 'uuid' var**
		uuid.noConflict = function() {
			_window.uuid = _previousRoot;
			return uuid;
		};

		_window.uuid = uuid;
	}
})('undefined' !== typeof window ? window : null);